Spotted hyenas are not a truly hermaphroditic species; the external genitalia of females and males are almost identical, making it difficult to distinguish their sexes.
Distinguishing Male and Female Spotted Hyenas
The external genitalia of female spotted hyenas is enlarged, resembling the size, shape, and position of male genitalia. Their urethras also open from above and can become erect. Interestingly, females have two structures that resemble “testicles,” with fused labia that conceal the external genital opening.
However, experienced wildlife experts find it relatively easy to differentiate between female and male spotted hyenas.
Firstly, there is a slight difference in the shape of the external genitalia between the sexes; males have pointed heads, while females have rounded heads, which can be observed when the hyenas are about three months old.
Secondly, when female spotted hyenas are nursing, their nipples become very visible, with no fur on top and the nipples being either black or partially pink.
Experienced experts can easily differentiate between female and male spotted hyenas.
Another distinguishing feature is that when viewed from the side, the “belly line” of female and male spotted hyenas differs, which is particularly noticeable in older individuals. The most protruding part of an older male’s belly is its stomach, creating a V-shaped belly line. In contrast, the most protruding part of a female’s belly is its nipples, located toward the rear of the belly, resulting in a line that slants from front to back.
Finally, when adult male and female spotted hyenas are together, they may be segregated by social status. Females hold a higher status than males, and as a result, males behave cautiously when approaching females—lowering their heads and folding their ears to show submission. Immature males receive support from their mothers and thus tend to act more aggressively, showing less fear towards females of lower status than their mothers.
Female spotted hyenas have a higher status than males.
Why Do Female Spotted Hyenas Develop This Way?
The reason lies in the biological mechanisms of female spotted hyenas, which provide extremely high concentrations of male hormones to their offspring during pregnancy. This impacts the development of the pups, making their physical growth, temperament, and behavior more masculine. Among these, the level of male hormones that the dominant female transmits to her daughters is higher than that in typical female hyenas, leading to a more aggressive nature in the dominant female’s offspring from a young age.
Spotted hyenas are also quite unique; most mammal species have males that are larger than females, but in spotted hyenas, females are larger than males. Female hyenas in East Africa weigh around 55 kg while males weigh about 50 kg; in South Africa, females weigh 70 kg compared to males at 60 kg. Spotted hyenas rank just behind lions, being the second-largest carnivores on the African savanna. Notably, only spotted hyenas exhibit such characteristics, while brown hyenas, striped hyenas, and wild dogs resemble other mammals in that males are larger than females, and females do not possess masculinized genitalia.
In spotted hyenas, females are larger than males.
The unique hermaphroditic characteristics of spotted hyenas affect all aspects of their lives. Firstly, unlike most mammal groups led by males, the dominant spotted hyena is always female, often referred to as the “queen hyena.” The status of a female in the clan is higher than that of males; even the lowest-ranking female has a higher status than the highest-ranking male in the clan. When the group feeds, the queen hyena is prioritized, followed by other females in order of their ranking, with males eating last.
The spotted hyena clan is matriarchal, where females remain in the clan upon maturity, while males are expelled upon reaching maturity. Matriarchal relationships govern the social lives of hyenas. A mother hyena gains higher status in the clan for every female pup she successfully rears. Moreover, status within the clan can be inherited across generations. Daughters can inherit their mother’s social rank, including the position of the dominant female, thus ensuring that the queen hyena title is passed down from generation to generation.
Matriarchal relationships govern the social lives of hyenas.
Secondly, the structure of female hyenas’ external genitalia makes mating very challenging, requiring the cooperation of the female. If a male hyena wants to mate, he must first please the female; when approaching her, he will behave very submissively and is more likely to succeed in mating if he makes the female feel satisfied with his submissive demeanor.
In reality, immature male hyenas can also enjoy their mother’s status, and they may kill lower-ranking adult females. However, other females in the clan will not accept them. Therefore, as male hyenas grow, they must leave their clan and integrate into other clans to serve females and become “obedient servants,” as this is the only way to gain mating rights. This mechanism helps spotted hyenas avoid inbreeding.
Spotted hyenas typically give birth to 1-2 pups per litter.
Finally, the unique structure of female hyenas’ genitalia makes giving birth very difficult; they lack an external opening in their reproductive tract, and thus they must tear their genitalia to allow their pups to emerge, resulting in significant injuries that take weeks to heal. Unfortunately, some less healthy females may die after their first birth.
Even though female hyenas have a high social status, they bear the responsibility of childbirth and raising the pups. They typically give birth to only 1-2 pups per litter. Newborn pups are often twice the size of lion cubs and five times that of polar bear cubs. The nutritional value of spotted hyena milk is the highest among terrestrial mammals, over four times that of goat milk, and they can nurse for up to one and a half years.
Moreover, when ungulates within the clan’s territory migrate, hyenas follow them in search of food, but they cannot take their pups along. Consequently, the mother hyena must return to the original location every three days to feed the pups—an average distance of 40 km one way, and they must make this journey 40 to 50 times a year.
